[Regarding launch of new MailChimp automation tools] "I have been evaluating a few email tools and getting ready to start testing. Why would someone use Customer.io instead of MailChimp?" --question on growthhackers.com

Gone are the days when there were 3-5 email vendors and you simply held your nose and picked the one that sucked least. Now with nearly 300 email service providers and counting, and the growth of CRM/Marketing Automation, we're seeing a blurring of the lines in the email service provider space.

To help break down this question, it's instructive to think about how companies use email:

Nurture: Increasing engagement and/or retention with customers via activity based "triggered" emails. For example: sending you an email when you haven't used the product in a month to get you to come back.

Spam Contacting potential customers via purchased lists. We hope you aren't doing this unless it's a legitimate source like a trade show, but it is being done.

Mailchimp: The Gorilla in The Room

New Focus: Nurture and Alert: With the Mandrill product MailChimp jumped head first into the automated trigger alert email space.

Even Newer Focus: With the launch of Automated eMails on MailChimp, they're merging Mandrill and Mailchimp, by working to bring a graphic user interface (GUI) to what was traditionally a highly technical job.

What the customers say:Mailchimp competes directly with Constant Contact in the entry level marketing space. That means everyone from your church to a startup uses it because it's free to use up to a certain point. Mandrill, it's more powerful brother (dare we say 800 lb gorilla?), is where you go when you're ready to "grow up" and automate. Autoresponder features in the core email app are strong addition and will encourage many more startups to stay with Mailchimp when growing up, vs. immediately switch to Mandrill, where they could be lost to Rackspace and others. Marketers have a love/hate relationship with MailChimp.

Customers Love: free pricing, easy to use GUI and lots of design templates, lots of integrations with other tools.

Customers Don't Love Opaque pricing once you do pay, lack of customer support when things go wrong, buggy templates.

Use Mailchimp When: you're brand new to email and have no budget and don't know what you're doing, or truly lack any technical resources to help you code or send email.

Customer.io: The Heavyweight Contender

Traditional Focus: Nurture and Alert Customer.io has been one of the most exciting entrants into ecommerce in a long time. They can see what customers are doing on your website, and help you target them with emails to help close the sale. This is something that was very hard to do before without a lot of technical support.

Came with the package: Convert: Inherent in the system was the ability to use user behavior to drive the conversion email rather than simply sending emails on a time basis after sign up.

What the customers say: We've yet to find clients who don't like this product. The longer a marketer has tried to work the old fashioned way with email, the greater their love. Startups are also using this tool to replace dashboards at first, freeing up developer time to focus on the core product.

Customers Love: free starter pricing, easy to use GUI, saving time on building dashboards and interactive customer experiences.

Customers Don't Love Once they get hooked on auto responders they want in app messaging and that doesn't exist here.

Use Customer.io When: You know what basic email etiquette is and want to start from scratch to build out the customer experience. Consider intercom.io as an alternative due to its in-app messaging capabilities.

What do you think of our comparison? Did we get it right? How are you using email? Let's talk about it on Twitter or the comments below.

Disclosures: TimeShareCMO accepts no money of any kind from vendors so that we can remain 100% independent from conflicts of interests. If we use a particular vendor, we pay for their service at published rates, and recieve no special consideration for our posts.